This invention relates to a process for preconditioning sand or a like material by altering its temperature and/or moisture content to maintain it in a granular form.
In an average winter, highway departments in the United States spread some ten million tons of salt to keep roads safe. The corrosive effects of the salt are well known but this objection has been dismissed with the argument that at $25.00 a ton for salt this method of road treatment is far cheaper than any alternative. However, the Environmental Protection Agency estimates that salt induced road damage and vehicle corrosion costs $3 billion a year.
While sand and gravel are good economical alternatives, one of the major problems in using these products is in keeping them from clumping or freezing together. When sand is wet or freezes together, it costs more to get it separated than the cost of the sand.
Currently, sand and gravel are kept free flowing during subzero temperatures by storing it in a warm building. Frozen sand and gravel must be screened and frequently mixed with salt to keep it useable.
Further, in moist climates it is necessary to reduce the moisture content of the sand to render it free flowing.